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Chem - A level (units 1 -10) > Chemical industry - Unit 6 > Flashcards

Chemical industry - Unit 6 Flashcards

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1
Q

What is meant by dynamic equilibirum?

A

1 - Rate of forward reaction equals rate of reverse reaction in a closed system

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2
Q

What do you talk about when asked ‘Comment on the choice of conditions’ (2)

A

1 - Yeild

2 - Rate

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3
Q

What is the effect of a catalyst on equillibrium?

A

1 - No effect on equillibirum

2 - Increases rate of forward and reverse reaction equally by providing alternative reaction pathway with a lower Ea

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4
Q

What is NH4+?

A

The ammonium ion

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5
Q

What is the name of N2O?

A

dinitrogen oxide

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6
Q

What is the apperance of NO, NO2, N2O?

A

NO = colourless gas, turns to brown NO2 in air

NO2 = brown gas

N2O = colourless gas

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7
Q

How is NO formed? (3)

A

1 - Combustion in engines

2 - Thunderstorms

3 - In soil by denitrofying bacteria

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8
Q

How is NO2 formed?

A

from oxidation of NO in atmosphere

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9
Q

How is N2O formed?

A

In soil by denitrfying bacteria

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10
Q

What is the reactivity of N2O, NO, NO2 (2)

A

NO + NO2 = most reactive as radicals

N2O = less reactive as not a radical

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11
Q

What is the test for a nitrate (V) ion and equation? (4)

A

1 - Add Davardas alloy - Al (reducing agent)

2 - Add NaOH

3 - Add sample to a test tube + heat

4 - NH3 gas turns damp red litmus paper blue

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12
Q

What is the test for ammonium ions? (3)

A

1 - Add NaOh to sample

2 - Add to test tube + heat

3 - NH3 gas will turn damp red litmus paper blue

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13
Q

How do you make sulfuric acid? (4)

A

1 - Extraction of sulfur

2 - Conversion of sulfur to sulfur dioxide

3 - Conversion of sulfur dioxide to sulfur trioxide

4 - Conversion of sulfur trioxide to sulfuric oxide

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14
Q

What is rate of a reaction?

A

How quickly reactants are converted into products

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15
Q

What are the experimental methods that can be used to measure the rate of reaction? (5)

A

1 - Volume gas produced - gas syringe

2 - Mass lost (gas lost)

3 - pH changes - pH probe

4 - Coloured product made or reactant used - colormetry

5 - Titration - taking samples at a known time - quenching samples (stop/slow down reaction) - titrate samples

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16
Q

What are the issues with measuring the mass lost of a gas?

A

The mass of the gas could be so little that the mass scale would not detect a loss in mass

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17
Q

How can you quench a smaple? (2)

A

1 - If acid you could add a base to neutralise reaction

2 - Sit on a bed of ice

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18
Q

What is the equations and catalyst for production of sulfuric acid? (3)

A

1 - S + O2 –> SO2

2 - SO2 + 1/2 O2 <—-> SO3 (contact process)

V2O5 (catalyst)

3 - SO3 + 1/2 O2 –> SO4

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19
Q

What are the possible units for rate? (3)

A

1 - moldm-3s-1

2 - cm3s-1

3 - gs-1

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20
Q

What is the use of rate equations?

A

Allow estimates to be made about the impact of a factor on the rate of a reaction without having to carry out experiments

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21
Q

What does the gradient of a graph give you?

A

The rate

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22
Q

Explain the rates on graph? (2)

A

1 - Steep gradient gives fast rate - conc. reactnat high

2 - Shallow gradient gives slow rate - conc. reactant falls

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23
Q

How can you find initial rate?

A

Draw a tangent to the curve at t=0

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24
Q

What does straight line graph mean?

A

rate directly proptional to conc. reactant

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25
Q

What is k (lower case) ?

A

rate constant

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26
Q

What does k vary with?

A

temp

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27
Q

Why could the units of k be the same for two different reactions?

A

Because the overall order if the two reactions is the same

28
Q

What is the unit of k when overall order of a reaction is 2nd order?

A

dm3mol-1s-1

29
Q

What is the unit of k when overall order of a reaction is 0 order?

A

moldm-3s-1

30
Q

What is the unit of k when overall order of a reaction is 1st order?

A

s-1

31
Q

What does it mean if a reaction is 1st order?

A

Doubling the conc. doubles the rate

32
Q

What does it mean if a reaction is 2nd order?

A

doubling the conc., quadruples the rate

33
Q

What does it mean if a reaction is 3rd order?

A

conc. has no effect on rate

34
Q

What is the most important factors for determining rate? (3)

A

1 - Most important - Ea

2 - Then temp

3 - Then conc.

35
Q

What is the Arrhenius used for?

A

To calulate the impact of changing:

1) Ea (by a catalyst)
2) Temp

on rate of reaction

36
Q

What happens to the rate of reaction with a 100c temp rise?

A

rate roughly doubled, (kx2)

37
Q

Describe effect of 100c temp rise on rate of reaction? (2)

A

1 - Number of collisions with energy =Ea or >Ea almost doubles

2 - So rate roughly doubles

38
Q

Describe the effect of decreasing the Ea on rate? (2)

A

1 - significantly increases the no of collisions with energy =Ea or >Ea

2 - Therefore increases rate

39
Q

How do you find the order of reaction WRT a certain reactant? (3)

A

1 - Draw a tangent at the origin of diff graphs + find graident to find initial rate values

2 - Plot initial rate against conc.

3 - Graphs shape will determine order

40
Q

What can the average rate of reaction be proportional to?

A

1/time

41
Q

What is T?

A

Temp

42
Q

What is t?

A

time

43
Q

How can half lives be used to detrmine order of reaction? (2)

A

1 - If half lives are constant then reaction 1st order

2 - 0 + 2nd order don’t have constant half lives

44
Q

What is the half-life?

A

The time taken for the conc. of a substance to half

45
Q

What is the rate-determining step?

A

The slowest step in the reaction mechanism

46
Q

How can the rate-equation be used to find info about the rds? (3)

A

1 - Sustances not in the rate equation are not in the rds, they are in a faster step

2 - Susbatances in rate equation are in rds

3 - Order of reaction WRT each substance will tell you realtive no. moles/molecules of the substance involved in the rds

47
Q

Why are some steps in a mechanims slower than others? (3)

A

1 - Step has a higher Ea

2 - Only, small no. reactants have >/= energy to overcome Ea each second + turn into products

3 - rate reaction slow

48
Q

Where can the rds occur in a multi-step mechanism?

A

rds can come at any point

49
Q

In a multi-step reaction, what will be the rds?

A

The step with the highest Ea

50
Q

How does the energy of intermediates + reactnts+ products of the same reaction compare?

A

Intermediates have higher energy than products + reactants

51
Q

What is a raw material, examples?

A

Something that is unprocessed

1 - Air

2 - Crude oil

3 - Natural gas

52
Q

What are feedstocks, example?

A

processed raw material

1 - Ethene

53
Q

What is a co-product?

A

Useful product of a reaction

54
Q

What is a by-product? (2)

A

1 - Not useful products made by secondary reactions

2 - Must be disposed of

55
Q

How can thermal energy be conserved?

A

Using heat exchangers

56
Q

What is a hazard?

A

The potential that a hazadrous substance has to cause harm

57
Q

What is a risk?

A

The liklihood the hazardous substance will cause harm under the conditions of its use

58
Q

What is the risk of flammable gases and control methods? (2)

A

1 - Explosions, fires

2 - Store in flameproof cyclinders

59
Q

What is the risk of acidic gases and control methods? (2)

A

1 - Burns

2 - Regular checking of plant for leaks

60
Q

What is the controls methods for toxic emmissions? (2)

A

1 - Monitor level of emmissions

2 - Evacuation procedures practiced

61
Q

How doe you turn NH3 into NH4+?

A

Add acid

62
Q

If something is 0 order does it go in the rate equation?

A

No

63
Q

What is the order of a substance if it is in a fast step?

A

0 order

64
Q

What is the order of a substance if it is in a slow step?

A

2nd or 1st

65
Q

If a reaction is endothermic and you increase the temp, what will happen to the yeild?

A

1 - Endothermic reaction dcreases temp

2 - Therefore, higher temp favours endothermic reaction

3 - Therefore yeild increases

66
Q

If a reaction is exothermic and you increase the temp, what will happen to the yeild?

A

1 - exothermic increase temp

2 - Therefore exothermic reaction not favoured

3 - Yield decreases

Chem - A level (units 1 -10) (14 decks)

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